[.github] Re-enable locking issues after 30 days of inactivity (#8655)

Context: 16e0943
Context: dotnet/maui#19145

When we migrated from FabricBot to GitOps.ResourceManagement due to
FabricBot being decommissioned (16e0943), we lost the rule:

  * [Closed Issue Management] Lock issues closed without activity for over 30 days

This rule is useful because comments on old, closed issues rarely
will be seen or responded to, making us seem unresponsive to users.

MAUI has replaced this rule (dotnet/maui#19145) with a GitHub Action
written by the VSCode team that runs daily and performs the locking.
We should ~~steal~~ borrow this for our own repos.

[0]: #8173

.github/workflows/locker.yml

@@ -0,0 +1,36 @@
+name: Locker - Lock stale issues and PRs
+on:
+  schedule:
+    - cron: '0 9 * * *' # Once per day, early morning PT
+
+  workflow_dispatch:
+    # Manual triggering through the GitHub UI, API, or CLI
+    inputs:
+      daysSinceClose:
+        required: true
+        default: "30"
+      daysSinceUpdate:
+        required: true
+        default: "30"
+
+permissions:
+  issues: write
+  pull-requests: write
+
+jobs:
+  main:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout Actions
+        uses: actions/checkout@v4
+        with:
+          repository: "microsoft/vscode-github-triage-actions"
+          path: ./actions
+          ref: cd16cd2aad6ba2da74bb6c6f7293adddd579a90e # locker action commit sha
+      - name: Install Actions
+        run: npm install --production --prefix ./actions
+      - name: Run Locker
+        uses: ./actions/locker
+        with:
+          daysSinceClose:  ${{ fromJson(inputs.daysSinceClose  || 30) }}
+          daysSinceUpdate: ${{ fromJson(inputs.daysSinceUpdate || 30) }}